1 mike 1.2 //%2006////////////////////////////////////////////////////////////////////////
2 //
3 // Copyright (c) 2000, 2001, 2002 BMC Software; Hewlett-Packard Development
4 // Company, L.P.; IBM Corp.; The Open Group; Tivoli Systems.
5 // Copyright (c) 2003 BMC Software; Hewlett-Packard Development Company, L.P.;
6 // IBM Corp.; EMC Corporation, The Open Group.
7 // Copyright (c) 2004 BMC Software; Hewlett-Packard Development Company, L.P.;
8 // IBM Corp.; EMC Corporation; VERITAS Software Corporation; The Open Group.
9 // Copyright (c) 2005 Hewlett-Packard Development Company, L.P.; IBM Corp.;
10 // EMC Corporation; VERITAS Software Corporation; The Open Group.
11 // Copyright (c) 2006 Hewlett-Packard Development Company, L.P.; IBM Corp.;
12 // EMC Corporation; Symantec Corporation; The Open Group.
13 //
14 // Permission is hereby granted, free of charge, to any person obtaining a copy
15 // of this software and associated documentation files (the "Software"), to
16 // deal in the Software without restriction, including without limitation the
17 // rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
18 // sell copies of the Software, and to permit persons to whom the Software is
19 // furnished to do so, subject to the following conditions:
20 //
21 // THE ABOVE COPYRIGHT NOTICE AND THIS PERMISSION NOTICE SHALL BE INCLUDED IN
22 mike 1.2 // ALL COPIES OR SUBSTANTIAL PORTIONS OF THE SOFTWARE. THE SOFTWARE IS PROVIDED
23 // "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT
24 // LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
25 // PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
26 // HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
27 // ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
28 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
29 //
30 //==============================================================================
31 //
32 //%/////////////////////////////////////////////////////////////////////////////
33
34 #ifndef Pegasus_Magic_h
35 #define Pegasus_Magic_h
36
37 #include <Pegasus/Common/Config.h>
38
39 PEGASUS_NAMESPACE_BEGIN
40
41 /** The Magic class implements a convenient way to use magic numbers in
42 user-defined classes. Magic numbers help detect use of uninitialized,
43 mike 1.2 destructed, or corrupted objects.
44
45 To instrument a class to use magic numbers simply add a class member
46 of type Magic<> as shown in thsi example:
47
48 \code
49 class MyClass
50 {
51 public:
52
53 MyClass();
54
55 ~MyClass();
56
57 void foo();
58
59 private:
60 Magic<0xC531B144> _magic;
61 };
62 \endcode
63
64 mike 1.2 Choose whatever number you like for a magic number. The number above was
65 generated by the Linux uuidgen utility (Windows has a utility with the
66 same name).
67
68 To test magic number, add the following expression wherever necessary
69 (usually as the first line of every member function).
70
71 \code
72 PEGASUS_ASSERT_DEBUG(_magic);
73 \endcode
74
75 Here's a typical example:
76
77 \code
78 MyClass::~MyClass()
79 {
80 PEGASUS_ASSERT_DEBUG(_magic);
81 }
82 \endcode
83
84 This tests whether the magic number is 0xC531B144 and asserts if it is
85 mike 1.2 not.
86
87 Note that using a magic number makes the user-defined class 4 bytes larger
88 but there is no run-time overhead unless you compile with PEGASUS_DEBUG.
89 The Magic constructor and destructor are empty without PEGASUS_DEBUG and
90 are discarded by the compiler.
91
92 CAUTION: You may be tempted to compile out the magic member when
93 PEGASUS_DEBUG undefined. However, this will causes unpredictable
94 behavior when debug libraries are mixed with non-debug libraries. The
95 structure alignment and size will be different and will lead to crashes.
96 This is only safe if a class is internal to a library.
97 */
98 template<Uint32 MAGIC_NUMBER>
99 class Magic
100 {
101 public:
102
103 /** Default constructor. Sets the magic number.
104 */
105 Magic()
106 mike 1.2 {
107 #ifdef PEGASUS_DEBUG
108 _magic = MAGIC_NUMBER;
109 #endif
110 }
111
112 /** Destructor. Clears the magic number (with the pattern 0xDDDDDDDD).
113 */
114 ~Magic()
115 {
116 #ifdef PEGASUS_DEBUG
117 _magic = 0xDDDDDDDD;
118 #endif
119 }
120
121 /** Allows magic number to be used as a boolean expression. This function
122 tests the magic number and return true if valid.
123 */
124 operator bool() const
125 {
126 #ifdef PEGASUS_DEBUG
127 mike 1.2 return _magic == MAGIC_NUMBER;
128 #else
129 return true;
130 #endif
131 }
132
133 private:
134 Uint32 _magic;
135 };
136
137 PEGASUS_NAMESPACE_END
138
139 #endif /* Pegasus_Magic_h */
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